2015 ISAKOS Biennial Congress ePoster #1722

Correction Accuracy in Medial Opening Wedge High Tibial Osteotomy Using Preoplan Software

David W. Elson, MBChB, MRCS, FRCS (T&O), Newcastle upon Tyne, Tyne & Wear UNITED KINGDOM
Melissa Mahoney, MBBS, BSc (Hons) MRCS, London UNITED KINGDOM
Alistair Ian Eyre-Brook, BM, BMedSci, Taunton UNITED KINGDOM
Sam K. Yasen, MBBS, MScEng, BSc, MRCS, FRCS(Tr&Orth), PGCE, Basingstoke, Hampshire UNITED KINGDOM
Bhushan Sabnis, FRCS, Basingstoke UNITED KINGDOM
George Cox, BMedSci, BMBS, Basingstoke, Hampshire UNITED KINGDOM
Nigel Rossiter, FRCS, Basingstoke, Hampshire UNITED KINGDOM
Michael J. Risebury, MBBS(Hons), MA(Hons), FRCS(Tr&Orth), Basingstoke, Hampshire UNITED KINGDOM
Adrian J. Wilson, FRCS, Basingstoke, Hants UNITED KINGDOM

North Hampshire Hospital,, Basingstoke, Hampshire, UNITED KINGDOM

FDA Status Not Applicable

Summary: This paper explores the surgical accuracy of HTO planned using PreOPlan software




Medial Opening Wedge High tibial osteotomy (MOW HTO) is performed for medial compartment arthritis with varus malalignment. Modern plating techniques are stable enough to support a medial opening wedge such that the osteotomy gap can be adjusted easily, during the procedure. Pre- operative planning with long leg alignment radiographs is mandatory. The reliability of PreOPlan digital planning software is high. However the accuracy of this software beyond the planning stage when surgically applied to each patient is unknown. This study aims to quantify accuracy by comparing the intended and achieved correction. The null hypothesis was inadequate corrections inconsistent with the intended plan.


Various factors will influence the intended correction which is usually aimed between neutral (50%) and Fujisawa’s point (62%) according to where the Mikulicz’ weight bearing line intersects the tibial width. Digital plans based upon an intended correction were generated for individual patients using PreOPlan software. MOW HTO was performed according to the correction angles and opening distances generated from PreOPlan. The achieved correction was judged from post operative long leg radiographs. The intended correction is subtracted from the achieved correction to generate surgical accuracy and the distribution of this variable is described.?


208 knees with available measurements who underwent MOW HTO from 189 patients (19 staged bilaterals) were included. The mean pre-operative Mikulicz point was 26.6% (3.4% to 53.7%) The mean intended correction was 58.4% (50.0% to 69.1%). The mean achieved correction was 56.6% (34.2% to 95%). 94 patients (45.2%) were within 5% of the intended correction, 56 patients (26.9%) were within 5-10%, 31 patients (14.9%) within 10-15%,18 patients (8.7%) within 15-20%, 8 patients (3.8%) within 20-30% and 1 patient (0.4%) within 30-40%. 86 were corrected positively with 122 corrected negatively.


This study quantifies the surgical accuracy of correction using measurements from PreOPlan where 72.1% of corrections were achieved within 10% of the intended plan. HTO surgery planned with PreOPlan usually achieves satisfactory corrections which are consisitent with the digital plan. This study should serve as a benchmark when compared to other methods for planning HTO.